I naively used to think that writers of short stories and essays simply didn't have enough good material to fill a traditional book. Fortunately some great teachers, and exposure to some of the best writers in the field, showed me the incredible art of short form writing.
The beauty of short works has become even more apparent as I've read too many books lately where I'm left feeling like a shorter essay or short story would've been more powerful. Often (like my college papers) they had a few great things to say but had used filler to make it fit a length requirement. As print magazines, the previous bastion of short form, are shutting their doors, I'm encouraged to see new outlets such as Kindle Singles and Ted Talks remind people that brevity can be a virtue.